题解

#include <bits/stdc++.h>
using namespace std;

int main(){
    string a,b;
    int sum = 0;
    cin >> a >> b;
    for (int i = 0;i < a.size();i++){
        if (a[i] == b[i]){
            sum++;
        }else{
           break; 
        } 
    }
    cout << sum;
    return 0;
}