#include <iostream>
#include<string>
#include<vector>
#include<queue>
#include<algorithm>
#include<iomanip>
typedef long long ll;
typedef double d;
using namespace std;
#define file
/*{freopen("input.text", "r", stdin);
freopen("output.text", "w", stdout);
}*/
ll arr[200005];
#define stop system("pause");
int main()
{
int n, m, a[256],sm=0;
char ar[120][120], c;
cin >> n >> m >> c;
for (int i = 1; i <= n; i++)
for (int j = 1; j <= m; j++)
cin >> ar[i][j];
for (int i = 1; i <= n; i++)
for (int j = 1; j <= m; j++)
if (ar[i][j] == c)
a[ar[i - 1][j]] = a[ar[i + 1][j]] = a[ar[i][j - 1]] = a[ar[i][j + 1]] = 1;
for (int i = 'A'; i <= 'Z'; i++)
sm += a[i];
cout << sm - a[c] << endl;
// stop;
}
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