main function cannot declare main to be global variable [closed]

Problem: Given an array of 4 digits, return the largest 24 hour time that can be made.

The smallest 24 hour time is 00:00, and the largest is 23:59. Starting from 00:00, a time is larger if more time has elapsed since midnight.

Return the answer as a string of length 5. If no valid time can be made, return an empty string.

Example 1:

Input: A = [1,2,3,4] Output: "23:41"

Solution

#include<iostream>
#include<vector>
#include<algorithm>
#include<iomanip>
#include<sstream>
using namespace std;


class Solution {
public:
string largestTimeFromDigits(vector<int>& A) {

    int max_time = -1;
    // prepare for the generation of permutations next.
    sort(A.begin(), A.end());

    do {
        int hour = A[0] * 10 + A[1];
        int minute = A[2] * 10 + A[3];
        cout << A[0] << ' ' << A[1] << ' ' << A[2] <<  ' '<<A[3]<< '\n';

        if (hour < 24 && minute < 60) {
            int new_time = hour * 60 + minute;
            max_time = new_time > max_time ? new_time : max_time;
            cout<< max_time<<endl;
        }
    } while(next_permutation(A.begin(), A.end()));

    if (max_time == -1) {
        return "";
    } else {
        ostringstream strstream;
        strstream << setw(2) << setfill('0') << max_time / 60
           << ":" << setw(2) << setfill('0') << max_time % 60;
        return strstream.str();
    }
}

};

//Driver code

int main{

vector <int> t1;
t1.push_back(1);
t1.push_back(2);
t1.push_back(3);
t1.push_back(4);

Solution obj1;
obj1.largestTimeFromDigits(t1);
return 0;

}

I got some errors in main function

How can I overcome this error?