#include <bits/stdc++.h>

using namespace std;

int main()
{
    int n;
    cin >> n;
    string s;
    cin >> s;
    int i = 0;
    int j = n - 1;
    int ans = 0;
    int c = 0;
    while(i < j){
        ++ans;
        if(c == 0){
            while(i < n && s[i] == 'm'){
                ++i;
            }
            while(j > -1 && s[j] == 'c'){
                --j;
            }
            c = 1;
        }
        else{
            while(i < n && s[i] == 'c'){
                ++i;
            }
            while(j > -1 && s[j] == 'm'){
                --j;
            }
            c = 0;
        }
    }
    cout << ans - 1 << endl;
}