#include <stdio.h>
#include <limits.h>

int main(void) {
	int N,i;
	scanf("%d",&N);
	unsigned long int b[1][N];
	unsigned long int a;
	a=1;
     for(i=0;i<N;i++){
       scanf("%lu*",&b[1][i]);}
    for(i=0;i<N;i++){
       a=a*b[1][i]; 
    }
    if(a>=10000000000000000)
    {printf("-1");}else{printf("%lu",&a);}
    
	return 0;
}