#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair <ll, ll> pii;
#define fi first
#define se second
#define pb push_back
const int MOD = 1e9 + 7;
const int MAX = 2e5 + 5;
const int dx[4] = {0, 0, 1, -1};
const int dy[4] = {1, -1, 0, 0};
#define int ll
signed main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
int n, m; cin >> n >> m;
char a[n + 5][m + 5];
for(int i = 1 ; i <= n ; i++){
for(int j = 1 ; j <= m ; j++){
cin >> a[i][j];
}
}
set <int> s;
for(int i = 1 ; i <= n ; i++){
for(int j = 1 ; j <= m ; j++){
if(a[i][j] == '.')continue;
s.insert(a[i][j]);
}
}
cout << s.size() << endl;
return 0;
}
