POJ1979.cpp

#include <iostream>
#include <algorithm>
#include <utility>
#include <map>
#include <queue>
#include <string>
#include <vector>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <ctime>
#include <cmath>

using namespace std;

#define FOR(i, j, k) for(int i = j; i < k; ++i)
#define rep(i, j) FOR(i, 0, j)
#define INF (1 << 30)

typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> P;
typedef pair<int, P> Pi;

const int MOD = 1e9 + 7;
const int dy[]={0, 0, 1, -1};
const int dx[]={1, -1, 0, 0};

template <class T> void chmin(T& a, const T& b) { a = min(a, b); }
template <class T> void chmax(T& a, const T& b) { a = max(a, b); }

int w, h, res = 0;
string s[21];
bool went[21][21];

void dfs(int x, int y) {
    ++res;
    went[y][x] = true;
    rep(i, 4) {
        int nx = x + dx[i], ny = y + dy[i];
        if(0 > nx || nx >= w || 0 > ny || ny >= h) continue;
        if(s[ny][nx] == '#' || went[ny][nx]) continue;
        dfs(nx, ny);
    }
} 

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);

    while(scanf("%d %d", &w, &h), w | h) {
        res = 0;
        int sx, sy;
        rep(i, h) cin >> s[i];
        rep(i, h) rep(j, w) {
            if(s[i][j] == '@') sx = j, sy = i;
        }
        memset(went, 0, sizeof(went));
        dfs(sx, sy);
        printf("%d\n", res);
    }
    return 0;
}