/*
* Created: 2022-06-05 19:50
*/
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
using namespace std;
using namespace chrono;
// using namespace atcoder
template <typename T>
using ordered_set =
tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
typedef long long ll;
typedef long double ld;
const ll inf = 1e18;
#define pii pair<int,int>
#define pll pair<ll,ll>
#define vi vector<int>
#define vll vector<ll>
#define rep(i, a, b) for(int i = (a);i<(b);i++)
#define repn(i, a, b) for(int i = (a);i>=(b);i--)
#define ss second
#define ff first
#define mkp make_pair
#define pb push_back
#define all(x) (x).begin(), (x).end()
template<typename T>
auto operator<<(ostream &os, T&v)->decltype(v.begin(), os){
os << "[";
int f = 0;
for(auto i:v) {
if(f++)os << ", ";
os << i;
}
os << "]";
return os;
}
template<typename F, typename S>
ostream& operator<<(ostream &os, pair<F, S> const &p) {
return os << "(" << p.first << ", " << p.second << ")";
}
ostream& operator<<(ostream &os, string& s) {
for(char i:s){
os << i;
}
return os;
}
void debug(){}
template<typename T, typename... V>
void debug(T t, V... v) {
cerr << t;
if(sizeof...(v)) {
cerr << ", "; debug(v...);
}
}
#ifdef LOCAL
#define dbg(x...) cerr << "[" << #x << "]: " << "["; debug(x); cerr << "]\n";
#else
#define dbg(x...)
#endif
void solve() {
int n, m;cin >> n >> m;
char c;
set<char> s;
for(int i = 0;i<n;i++) {
for(int j = 0;j<m;j++) {
cin >> c;
if(c!='.')s.insert(c);
}
}
cout<<s.size();
}
int main () {
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int t = 1;
//~ cin >> t;
while(t--) {
solve();
}
return 0;
}
