import java.util.Scanner;public class Main {public static void main(String[] args) {Scanner scanner = new Scanner(System.in);while (scanner.hasNext()) {long l = scanner.nextLong();long r = scanner.nextLong();long sum = 0;sum = sum_tribonacci(l, r);System.out.println(sum % 1000000007);
//          for (long i = 0; i <= 100l; i++) {
//              sum = sum_tribonacci(0, i);
//              System.out.println(i + "---------------------------" + sum
//                      % 1000000007l);
//          }}}public static long sum_tribonacci(long l, long r) {long n1 = 0, n2 = 0, n3 = 0;long u1, u2;long sum = 0;if (r < 3) {return (r - l + 1);}n1 = 0;n2 = 1;n3 = 2;// n1 = 1;// n2 = 1;// n3 = 1;long n4 = 0;if (l < 3) {// for (long i = 3; i <= r; i++) {for (long i = 3; i <= r + 1; i++) {n4 = n3 + n2 + n1;n1 = n2;n2 = n3;n3 = n4;}sum = n3 - l;return sum;} else {// for (long i = 3; i <= l; i++) {for (long i = 3; i <= l; i++) {n4 = n3 + n2 + n1;n1 = n2;n2 = n3;n3 = n4;}long sum1 = n3;// sum+=n4;for (long i = l + 1; i <= r + 1; i++) {n4 = n3 + n2 + n1;n1 = n2;n2 = n3;n3 = n4;}long sum2 = n3;return sum2 - sum1;}}}

  1 import java.math.BigDecimal;2 import java.util.Scanner;3 4 public class CopyOfMain2 {5     public static BigDecimal i1000000007 = new BigDecimal(6             String.valueOf(1000000007));7     //这里定义了四个数，其实是为了下面BigDecimal数组的初始化做准备8     public static BigDecimal i3 = new BigDecimal(String.valueOf(3));9     public static BigDecimal i2 = new BigDecimal(String.valueOf(2));10     public static BigDecimal i1 = new BigDecimal(String.valueOf(1));11     public static BigDecimal i0 = new BigDecimal(String.valueOf(0));12 13     public static void main(String[] args) {14         Scanner scanner = new Scanner(System.in);15 16         while (scanner.hasNext()) {17 18             long l = scanner.nextLong();19             long r = scanner.nextLong();20             BigDecimal[] sum = {i0,i0};21 22 23             sum = Tribonacci(l, r).divideAndRemainder(i1000000007);24             if(sum[1].longValue()<0)System.out.println(sum[1].add(i1000000007));25             else System.out.println(sum[1]);26             //这是比较笨的方法，用这种遍历的求和方式当然会超时27             // for (long i = l; i <= r; i++) {28             //    sum += Tribonacci(i);29             // }30             // for(long i =0; i <= 100l; i++){31             //    sum=Tribonacci(0,i);32             //    System.out.println(i+"---------------------------"+sum %33             //    1000000007l);34             // }35         }36     }37 38     public static BigDecimal Tribonacci(long l, long r) {39         BigDecimal sum = i0;40         if (r < 3) {41             for (long i = l; i <= r; i++) {42                 sum = new BigDecimal(String.valueOf(r - l + 1));43             }44             return sum;45         }46         BigDecimal[][] base = { { i1, i1, i0 }, { i1, i0, i1 }, { i1, i0, i0 } };47         if (l >= 3l) {48             BigDecimal[][] res1 = matrixPower(base, l - 3);49 50             BigDecimal[][] res = matrixPower(base, r - 2);51             // long[][] res = muliMatrix(res1,matrixPower(base, r- l+1));52             return (res[0][0].subtract(res1[0][0])).multiply(i3)53                     .add((res[1][0].subtract(res1[1][0])).multiply(i2))54                     .add((res[2][0].subtract(res1[2][0])));55         } else {56             BigDecimal[][] res = matrixPower(base, r - 2);57             return (res[0][0].multiply(i3).add(res[1][0].multiply(i2))58                     .add(res[2][0]).subtract(new BigDecimal(String.valueOf(l))));59         }60 61     }62     //求Tribonacci数列每一项的方法63     // public static long Tribonacci(long n) {64     // if (n == 0l || n == 1l || n == 2l) {65     // return 1;66     // } else if (n == 3l)67     // return 3;68     // long[][] base = { { 1l, 1l, 0l}, { 1l, 0l, 1l }, { 1l, 0l, 0l } };69     // long sum = 0l;70     //71     // long[][] res = matrixPower(base, n - 3l);72     //73     // return 3l * res[0][0] + res[1][0] + res[2][0];74     // }75 76     public static BigDecimal[][] matrixPower(BigDecimal[][] base, long p) {77         BigDecimal[][] res = new BigDecimal[base.length][base[0].length];78         for (int i = 0; i < res.length; i++) {79             for (int j = 0; j< res[0].length; j++) {80                 if (i == j) {81                     res[i][j] = i1;82                 } else83                     res[i][j] = i0;84             }85 86         }87         BigDecimal tmp[][] = base;88         for (; p != 0; p >>= 1) {89             if ((p & 1) != 0) {90                 res = muliMatrix(res, tmp);91             }92             tmp = muliMatrix(tmp, tmp);93         }94         return res;95     }96 97     private static BigDecimal[][] muliMatrix(BigDecimal[][] m1,98             BigDecimal[][] m2) {99         BigDecimal[][] res = new BigDecimal[m1.length][m2[0].length];
100         for (int i = 0; i < res.length; i++) {
101             for (int j = 0; j< res[0].length; j++) {
102                 res[i][j] = i0;
103             }
104         }
105         for (int i = 0; i < m1.length; i++) {
106             for (int j = 0; j < m2[0].length; j++) {
107                 for (int k = 0; k < m2.length; k++) {
108
109                         res[i][j] = res[i][j].add(m1[i][k].multiply(m2[k][j])).divideAndRemainder(i1000000007)[1];
110
111                 }
112             }
113         }
114         return res;
115
116     }
117
118 }