Untitled

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

int main() {
    int n, upperBound = -1;
    bool breakNow = false;
    vector<string> stringList;
    cin >> n;
    for(int i = 0; i < n; ++i) {
        string str;
        cin >> str;
        stringList.push_back(str);
    }
    for(int i = 0; ; ++i) {
        char currentLetter;
        if(i >= stringList[0].size()) {
            upperBound = i - 1;
            break;
        }
        else {
            currentLetter = stringList[0][i];
        }
        for(int j = 1; j < stringList.size(); ++j) {
            if(i >= stringList[j].size() || stringList[j][i] != currentLetter) {
                breakNow = true;
                upperBound = i - 1;
            }
        }
        if(breakNow) break;
    }
    if(upperBound == -1) {
        cout << "ans : "
    }
    else {
        cout << "ans : " << stringList[0].substr(0, upperBound + 1);
    }
    return 0;
}