60分求助

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

int n;
string s1;

int main()
{
	cin>>n;
	string s2[n];
	for(int i = 1; i <= n; i++)
	{
		cin>>s1;
		for(int j = 1; j <= s1.length() - 1; j++)
		{
			if('A' <= s1[j] && s1[j] <= 'Z')
			{
				s1[j] = s1[j] - 'A' + 'a';
			}
		}
		s2[i] = s1;
	}
	
	int x[n];
	for(int i = 1; i <= n; i++)
	{
		for(int j = 1; j  <= n; j++)
		{
			if(s2[i] = s2[j])
			{
				x[i]++;
			}
		}
	}
	
	int maxx = 0;
	for(int i = 1; i <= n; i++)
	{
		if(x[i] > maxx)
		{
			maxx = x[i];
		}
	}
	string s3 = s2[maxx];
	for(int j = 1; j <= s3.length() - 1; j++)
	{
		if('A' <= s3[j] && s3[j] <= 'Z')
		{
			s3[j] = s3[j] - 'A' + 'a';
		}
	}
	cout<<s3<<endl;
 	return 0;
}