#include <stdio.h>
int main(void) {
int a, b, c, d, e, min,max,n;
scanf("%d%d%d%d%d", &a, &b, &c, &d, &e);
min=a;
if(b<min)min=b
if(c<min)min=c
if(d<min)min=d
if(e<min)min=e
max = a;
if (max < b)
max = b;
if (max < c)
max =c;
if (max < d)
max=d;
if (max<e)
max=e;
n=max*min;
printf("%d", n);
return 0;
}