#include<stdio.h>
int main(){
    int n,i,j;
    scanf("%d",&n);
    if(n<=0){
        printf("Invalid input");
        return 0;
    }

int arr[100];
for(int i=0; i<n; i++){
    scanf("%d",&arr[i]);
}
for(i=0;i<n;i++){
    int count=0;
    for(int j=0;j<n;j++){
        if(arr[i]) = = arr[j];
        count++;
    }
if(count! = = 1){
    printf("%d",arr[i]);
}
return 0;
}