思路：

// 题意：输入一个字符矩阵，统计字符@组成多少个四连块
#include<cstdio>
#include<cstring>
const int maxn = 100 + 5;

char pic[maxn][maxn];
int m, n, idx[maxn][maxn];

void dfs(int r, int c, int id) {
    if (r < 0 || r >= m || c < 0 || c >= n)
        return;
    if (idx[r][c] > 0 || pic[r][c] != '@')
        return;
    idx[r][c] = id;
    for (int dr = -1; dr <= 1; dr++)
        for (int dc = -1; dc <= 1; dc++)
            if (dr != 0 || dc != 0)//出发点跳过
                dfs(r + dr, c + dc, id);
}

int main() {
    while (scanf("%d%d", &m, &n) == 2 && m && n) {
        for (int i = 0; i < m; i++) scanf("%s", pic[i]);
        memset(idx, 0, sizeof(idx));
        int cnt = 0;
        for (int i = 0; i < m; i++)
            for (int j = 0; j < n; j++)
                if (idx[i][j] == 0 && pic[i][j] == '@') 
                    dfs(i, j, ++cnt);
        printf("%d\n", cnt);
    }
    return 0;
}