题解在此

建议降红

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