#include <bits/stdc++.h>
#define ff first
#define ss second
#define pb push_back
#define mp make_pair
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<ll, ll> pll;
typedef pair<ull, ull> pull;
typedef pair<int, int> pii;
typedef pair<ld, ld> pld;
int n, m;
int a[3009][3009];
int cl(int x, int y){
return(a[x][y] == 1 && a[x][y+1] == 2 && a[x][y+2] == 3);
}
int cd(int x, int y){
return(a[x][y] == 1 && a[x+1][y] == 2 && a[x+2][y] == 3);
}
vector<pii> v;
int sf(pii x, pii y){
if(x.ff + x.ss != y.ff + y.ss)
return x.ff + x.ss < y.ff + y.ss;
return x.ss < y.ss;
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
//freopen("in.txt", "r", stdin);
//freopen("out.txt", "w", stdout);
cin >> n >> m;
string s;
for(int i = 0; i < n; ++i){
cin >> s;
for(int j = 0; j < m; ++j){
if(s[j] == 'R')
a[i][j] = 1;
else if(s[j] == 'G')
a[i][j] = 2;
else
a[i][j] = 3;
v.pb({i, j});
}
}
sort(v.begin(), v.end(), sf);
int ans = 0;
for(auto u : v){
int i = u.ff;
int j = u.ss;
if(cl(i, j)){
++ans;
a[i][j] = a[i][j+1] = a[i][j+2] = 0;
}
else if(cd(i, j)){
++ans;
a[i][j] = a[i+1][j] = a[i+2][j] = 0;
}
}
cout << ans << '\n';
}
