题解

#include<iostream>
#include<string>
using namespace std;
int main(){
    string s;
    cin>>s;
    int cnt=0;
    for(int i=0;i<=s.size()-4;i++){
        if(s[i]=='N'&&s[i+1]=='O'&&s[i+2]=='O'&&s[i+3]=='N'){
            cnt++;
        }
    }
    cout<<cnt;
    return 0;
}