#include <iostream>
#include <string>
#include <ctype.h>
using namespace std;
 
int main(){
	string str;
	int num_of_cur = 0, num_of_max = 0, size_of_max = 0, size;
	bool flag = true;
 
	while(cin >> str) 
	{
		num_of_cur++;
		if(isalnum(str[str.size()-1])) size = str.size();
		else size = str.size()-1;
 
		for(int i = 0; i<size/2 && flag; i++) 
		{
			if(str[i] != str[size-i-1]) 
			{
				flag = false;
			}
		}
		if(flag && size >= size_of_max) num_of_max = num_of_cur;
	}
 
	cout << num_of_max;
 
	return 0;
}

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

T28sIGl0IGFhYSBpcyBub3QgYmIu

Oo, it aaa is not bb.