1 #include <iostream>
 2 #include <cstdio>
 3 #include <cstring>
 4 #include <queue>
 5 #include <map>
 6 #include <ctime>
 7 #include <cmath>
 8 #include <algorithm>
 9 using namespace std;
10 #define INF 1000000
11 char str[200000];
12 int dp[200000];
13 int pre[200000];
14 int que1[200000];
15 int que2[200000];
16 int judge(char s)
17 {
18     if(s <= 'Z'&&s >= 'A')
19         return 1;
20     else if(s <= 'z'&&s >= 'a')
21         return 1;
22     else if(s == ' ')
23         return 1;
24     else
25         return 0;
26 }
27 int main()
28 {
29     int n,m,i,j,len,str1,end1,str2,end2;
30     scanf("%d%d%*c",&n,&m);
31     gets(str);
32     len = strlen(str);
33     for(i = 0; i < len; i ++)
34     {
35         if(judge(str[i]))
36         {
37             for(j = i; j < len; j ++)
38             {
39                 if(judge(str[j]))
40                 pre[j] = i;
41                 else
42                 {
43                     i = j;
44                     break;
45                 }
46             }
47             if(j == len) break;
48         }
49     }
50     for(i = 1;i <= len;i ++)
51     dp[i] = INF;
52     str1 = 0;end1 = 1;
53     str2 = 0;end2 = 1;
54     que1[0] = que2[0] = 0;
55     for(i = 1;i <= len;i ++)
56     {
57         dp[i] = dp[que1[str1]] + 1;
58         if(judge(str[i-1]))
59         {
60             if(str2 < end2)
61             dp[i] = min(dp[i],dp[que2[str2]]+1);
62         }
63         else
64         {
65             str2 = end2 = 0;
66         }
67         if(i == len) continue;
68         while(str1 < end1&&dp[i] <= dp[que1[end1-1]])
69         end1 --;
70         que1[end1++] = i;
71         while(str1 < end1&&i - que1[str1] >= n)
72         str1 ++;
73         if(judge(str[i]))
74         {
75             while(str2 < end2&&dp[i] <= dp[que2[end2-1]])
76             end2 --;
77             que2[end2++] = i;
78             while(str2 < end2&&que2[str2] < pre[i])
79             str2 ++;
80             while(i - que2[str2] >= m&&str2 < end2)
81             str2 ++;
82         }
83     }
84     printf("%d\n",dp[len]);
85     return 0;
86 }