#include <bits/stdc++.h>

using namespace std;

#define DPRINTF(...) printf(__VA_ARGS_)
#define FOR0(i, n) for(int i=0;i<=n;i++)
#define ALL(c) (begin(c)), (end(c))
#define fst(t) get<0>(t)
#define snd(t) get<1>(t)
#define thd(t) get<2>(t)

typedef long long ll;

int main(){
    std::string S;
    cin >> S;

    printf("%d\n", count(ALL(S), 'n'));
}