#include <cstdio>

int n;
char str[70010];

int main() {
    freopen("become.in", "r", stdin);
    freopen("become.out", "w", stdout);
    scanf("%d", &n);
    scanf("%s", str + 1);
    
    int ans = 0;
    for (int i = 1, cnt = 0; i <= n; ++i, cnt = 0) {
        for (; str[i] == 'e'; ++i, ++cnt);
        if (cnt) ans += 2 + 2 * cnt;
    }
    
    printf("%d\n", ans);
    return 0;
}