#include<stdio.h>
int main();
int n;
scanf("%d",&n);
if(n<1){
    printf("invalid input");
    return 0;
}
int ids[n];
for(int i=0;i<n;i++){
    scanf("%d",&ids[i]);
}
int foundduplicate=0;
int printed[200]={0};

for(int i=0;i<n;i++){
    int count=0;
    for(int j=i+1;j<n;j++){
        if(ids[i]==ids[j]){
            count++;
        }
    }
    if(count>0&&printed[ids[i]+1000]==0){
        printed[ids[i]+1000]=1;
        foundduplicate=1;
    }
}
return 0;
    }
}