CF 6B President's Office

#include <iostream>
#include <cstring>

using namespace std;

int n,m;
int sum[30],tx[4]={0,0,1,-1},ty[4]={1,-1,0,0};
char pd;
char data[105][105];
void solve(int i,int j)
{
if(i<0||i>=n||j<0||j>=m)
return ;
if(data[i][j] =='.')
return ;
if(data[i][j] != pd && data[i][j] != '.')
{
sum[data[i][j]-'A']++;
return ;
}
if(data[i][j] == pd)
{
data[i][j] = '.';
for(int k = 0;k < 4;k ++)
{
solve(tx[k]+i,ty[k]+j);
}
}
}
int main()
{
memset(sum,0,sizeof(sum));
while(cin>>n>>m>>pd)
{
for(int i = 0;i < n;i ++)
cin>>data[i];
for(int i = 0;i < n;i ++)
{
for(int j = 0;j < m;j ++)
{
if(data[i][j] == pd)
{
solve(i,j);
}
}
}
int ans = 0;
for(int i =0 ;i < 26;i ++)
{
if(sum[i])
ans++;
}
cout<<ans<<endl;
}
return 0;
}