#include <stdio.h>
using namespace std;

FILE *f = fopen( "elmaj.in", "r" );
FILE *g = fopen( "elmaj.out", "w" );

long long N;
long long a;
long long nr, s;

int main()
{
    int i;

    fscanf( f, "%d%d", &N, &a );
    nr = a;

    for ( i = 2; i <= N; i++ )
    {
        fscanf( f, "%d", &a );

        if ( a == nr ) s++;
        else           s--;

        if ( s == 0 )
            nr = a;
    }

    if ( s >= 0 )
        fprintf( g, "%d\n", nr );
    else
        fprintf( g, "-1\n" );

    fclose(f);
    fclose(g);
    return 0;
}