题解

#include<bits/stdc++.h>
using namespace std;
string s;
int cnt;
int main(){
    cin>>s;
    int n=s.size();
    for(int i=0;i<n;i++){
        if(s[i]=='N'&&s[i+1]=='O'&&s[i+2]=='O'&&s[i+3]=='N'){
            cnt++;
        }
    }
    cout<<cnt;
    return 0;
}