/*
//\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\\
\\ //
// 271828___182845__904523__53602__ \\
\\ 87___47____13______52____66__24_ //
// 97___75____72______47____09___36 \\
\\ 999595_____74______96____69___67 //
// 62___77____24______07____66__30_ \\
\\ 35___35____47______59____45713__ //
// \\
\\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\//
*/
#include <iostream>
#include <vector>
#include <set>
#include <map>
#include <unordered_map>
#include <unordered_set>
#include <cmath>
#include <climits>
#include <algorithm>
#include <random>
#include <queue>
#include <deque>
#include <iomanip>
#include <string>
#include <tuple>
#include <bitset>
#include <chrono>
#include <ctime>
#include <fstream>
#include <stack>
#include <cstdio>
#include <functional>
using namespace std;
using LL = long long;
const int N = 1e5 + 5;
const LL mod = 1e9 + 7, inf = 1e18;
vector<int> dx = { 1, 0, -1, 0, 1, -1, 1, -1 };
vector<int> dy = { 0, -1, 0, 1, -1, 1, 1, -1 };
void solve() {
int n, m; cin >> n >> m;
vector<string> v(n);
for(int i = 0; i < n; ++i){
cin >> v[i];
}
set<char> st;
for(int i = 0; i < n; ++i){
for(int j = 0; j < m; ++j){
if(v[i][j] != '.'){
st.insert(v[i][j]);
}
}
}
cout << st.size() << "\n";
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
// int t; cin >> t; while (t--)
solve();
}
