1 //#define LOCAL
 2 #include <iostream>
 3 #include <cstdio>
 4 #include <cstring>
 5 #include <algorithm>
 6 using namespace std;
 7
 8 const int maxn = 1010;
 9 char map[maxn][maxn];
10 int h[3][maxn], l[3][maxn], r[3][maxn];
11
12 int main(void)
13 {
14     #ifdef LOCAL
15         freopen("2870in.txt", "r", stdin);
16     #endif
17
18     int row, col;
19     while(scanf("%d%d", &row, &col) == 2)
20     {
21         int i, j, k, t;
22         for(i = 0; i < row; ++i)
23             scanf("%s", map[i]);
24         memset(h, 0, sizeof(h));
25         int ans = 0;
26         for(i = 0; i < row; ++i)
27         {
28             for(j = 0; j < col; ++j)
29             {
30                 switch(map[i][j])
31                 {    //处理h数组
32                     case 'a':
33                         ++h[0][j], h[1][j] = h[2][j] = 0;
34                         break;
35                     case 'b':
36                         ++h[1][j], h[0][j] = h[2][j] = 0;
37                         break;
38                     case 'c':
39                         ++h[2][j], h[0][j] = h[1][j] = 0;
40                         break;
41                     case 'w':
42                         ++h[0][j], ++h[1][j], h[2][j] = 0;
43                         break;
44                     case 'x':
45                         ++h[1][j], ++h[2][j], h[0][j] = 0;
46                         break;
47                     case 'y':
48                         ++h[0][j], ++h[2][j], h[1][j] = 0;
49                         break;
50                     case 'z':
51                         ++h[0][j]; ++h[1][j], ++h[2][j];
52                 }
53             }
54             l[0][0] = l[1][0] = l[2][0] = 0;
55             r[0][col-1] = r[1][col-1] = r[2][col-1] = col-1;
56             for(j = 1; j < col; ++j)
57                 for(k = 0; k < 3; ++k)
58                 {
59                     t = j;
60                     while(t > 0 && h[k][j] <= h[k][t-1])
61                         t = l[k][t-1];
62                     l[k][j] = t;
63                 }
64
65             for(j = col-2; j >= 0; --j)
66                 for(k = 0; k < 3; ++k)
67                 {
68                     t = j;
69                     while(t < col-1 && h[k][j] <= h[k][t+1])
70                         t = r[k][t+1];
71                     r[k][j] = t;
72                 }
73
74             for(j = 0; j < col; ++j)
75                 for(k = 0; k < 3; ++k)
76                     ans = max(ans, (r[k][j]-l[k][j]+1)*h[k][j]);
77         }
78         printf("%d\n", ans);
79     }
80     return 0;
81 }