#include<bits/stdc++.h>
using namespace std;
constexpr int maxn = 3e3+10;
int grid[maxn][maxn], n, m;
inline int pos(int i, int j) { return m*i+j; }
struct DSU
{
int pai[maxn], peso[maxn], hor[maxn], ver[maxn];
DSU() {for(int i = 0; i < maxn; i++) pai[i] = i, peso[i] = 1;}
int find(int x) { return pai[x]==x?x:pai[x]=find(pai[x]); }
void merge(int i, int j, int s) {
if(s) {
hor[find(pos(i,j))]++;
join(pos(i, j), pos(i, j-1));
join(pos(i, j), pos(i, j-2));
}
else {
ver[find(pos(i,j))]++;
join(pos(i, j), pos(i-1, j));
join(pos(i, j), pos(i-2, j));
}
}
void join(int a, int b) {
a = find(a), b = find(b);
if(a == b) return;
if(peso[a] < peso[b])
swap(a, b);
pai[b] = a;
peso[a] += b;
hor[a] += hor[b];
ver[a] += ver[b];
}
} dsu;
int main() {
scanf("%d %d", &n, &m);
for(int i = 0; i < n; i++) {
for(int j = 0; j < m; j++) {
char c; scanf(" %c", &c);
grid[i][j] = (c=='R'?0:c=='G'?1:2);
}
}
for(int i = 0; i < n; i++) {
for(int j = 0; j < m; j++) {
if(i >= 2 && grid[i][j] == 2 && grid[i-1][j] == 1 && grid[i-2][j] == 0)
dsu.merge(i, j, 0);
if(j >= 2 && grid[i][j] == 2 && grid[i][j-1] == 1 && grid[i][j-2] == 0)
dsu.merge(i, j, 1);
}
}
int ans = 0;
for(int i = 0; i < n*m; i++) {
if(dsu.find(i) == i)
ans += max(dsu.hor[i], dsu.ver[i]);
}
printf("%d\n", ans);
}
