#include <bits/stdc++.h> using namespace std; #define pb push_back #define ins insert #define lb lower_bound #define F first #define S second #define sz size() #define int long long #define in insert #define len(x) (int)x.size() #define all(v) v.begin(),v.end() #define FOR(x, n, m, d) for(int x = n; x <= m; x += d) #define FORR(x, n, m, d) for(int x = n; x >= m; x -= d) #define nikita ios_base::sync_with_stdio(0), cin.tie(0); const int N = 1e6 + 15; int a[N], b[N], n, m, x, y, l, r, k, inf = 1e18, ans, sum, c[N]; void solve(){ cin >> n >> m; set<char>st; string s; FOR(i, 1, n, 1){ cin >> s; FOR(j, 0, m-1, 1){ if(s[j] == '.')continue; st.in(s[j]); } } cout << st.sz; } signed main(){ nikita int tt = 1; // if(tt)cin >> tt; FOR(i, 1, tt, 1)solve(); }