fzu 1001 Duplicate Pair

#include<stdio.h>#include<string.h>#include<algorithm>using namespace std;int a[1000000+5];int main(){    int n,i,t,ans;    while(~scanf("%d",&n))    {        memset(a,0,sizeof(a));        for(i=0;i<n;i++)        {            scanf("%d",&t);            a[t]++;            if(a[t]==2) ans=t;        }        printf("%d\n",ans);    }    return 0;}