the number of subsequences "QAQ" in the string

#include<bits/stdc++.h>
#define endl "\n"

using namespace std;

int main() {
    int c = 0;
    string s1;
    cin >> s1;

    if(s1.size() == 1) {
        cout << 0;
    } else {
        for(int i=0; i<s1.size()-2; i++) {
            if(s1[i] == 'Q') {
                for(int j=i+1; j<s1.size()-1; j++) {
                    if(s1[j] == 'A') {
                        for(int k = j+1; k<s1.size(); k++) {
                            if(s1[k] == 'Q') {
                                c++;
                            }
                        }
                    }
                }
            }
        }
        cout << c;
    }


}