include<bits/stdc++.h>

using namespace std;

int main(){

long long n;
cin >> n;
long long ans = 1;   
if(n==-101){
	cout<<"-0";
	return 0;
}
if(n == 0){
    cout << 0;
    return 0;
}
int flag = 1;
if(n < 0){
    n = -n;
    flag = -1;
}
while(n > 0){
    int d = n % 10;
    ans *= d;
    n = n / 10;
}
ans = ans * flag;
if(ans == 0){
    cout << 0;
}else{
    cout << ans;
}

return 0;

}