#include <stdio.h>
#include <iostream>

using namespace std;

#define MAX 400

int n, m, a[MAX], c[MAX], best = 9999999, cul;

int main()
{
    FILE *fin = fopen("culori.in", "r");
    fscanf(fin, "%d", &n);
    for (int i = 1; i <= 2*n-1; ++i)
    {
        fscanf(fin, "%d", &cul);
        c[cul]++;
    }
    fclose(fin);
    
    for (int i = 1; i <= 300; ++i)
        if (c[i])
            if (best > c[i])
                best = c[i];
    FILE *fout = fopen("culori.out", "w");
    fprintf(fout, "%d\n", (best-1)*2);
    fclose(fout);
    
    return 0;
}