poj 1740 A New Stone Game

#include <iostream>#include <cstdio>#include <cstdlib>#include <cstring>using namespace std;bool f[1005];int main(){    int n;    while (scanf("%d", &n), n)    {        memset(f, 0, sizeof(f));        int ans = 0;        for (int i = 0; i < n; i++)        { int a; scanf("%d", &a); if (f[a])     ans--; else     ans++; f[a] = !f[a];        }        if (ans) printf("1n");        else printf("0n");    }    return 0;}