zoj 2100 Seeding

#include<stdio.h>char map[8][8];int visited,flag;int n,i,j,m;void dfs(int x,int y){    if( x<0 || y<0 || x>=n || y>=m)        return;    if(map[x][y]!='.')          return;    if(flag)         return;    map[x][y] = 'S';    visited++;    if(visited == n*m)    {        flag=1;        return;    }    dfs(x+1,y);     dfs(x-1,y);    dfs(x,y+1);    dfs(x,y-1);    visited--;    map[x][y]='.';}int main(void){    while(scanf("%d%d",&n,&m) && n && m)    {        for(i=0;i<n;i++) scanf("%s",map[i]);        for(i = 0 , visited = 0 ; i < n ; i++) for(j = 0;j<m;j++)     if(map[i][j]=='S')          visited++;        flag = 0;        dfs(0,0);        if(flag) printf("YESn");        else printf("NOn");    }      return 0;}