题解

#include<bits/stdc++.h>
using namespace std;
int main(){
    string s;
    cin >> s;
    long long cnt = 0, sum = 0;
    for(int i = 0; i < s.size(); i++){
        if(s[i] == 'z')
            cnt++;
        if(s[i] == 'y'){
            sum += cnt * (cnt - 1) / 2;
        }
    }
    cout << sum;
	return 0;
}