CodeForces 584A

C -C
Crawling in process...Crawling failed
Time Limit:1000MS    Memory Limit:262144KB    64bit IO Format:%I64d & %I64u
SubmitStatusPractice

CodeForces 584A

Description

Olesya loves numbers consisting of n digits, and Rodion only likes numbers that are divisible byt. Find some number that satisfies both of them.

Your task is: given the n and
t print an integer strictly larger than zero consisting of
n digits that is divisible by t. If such number doesn't exist, print - 1.

Input

The single line contains two numbers, n andt (1 ≤ n ≤ 100,2 ≤ t ≤ 10) — the length of the number and
the number it should be divisible by.

Output

Print one such positive number without leading zeroes, — the answer to the problem, or - 1, if such number doesn't exist. If there are multiple possible answers, you are allowed to print any of them.

Sample Input

Input

3 2

Output

712

思路：水题，一想便知；

#include<cstdio>
int main()
{
int n,t,i;
scanf("%d %d",&n,&t);
if(n==1 && t==10)
printf("-1\n");
else if(t==10)
{
printf("1");
for(i=0;i<n-1;i++)
printf("0");
printf("\n");
}
else
{
for(i=0;i<n;i++)
{
printf("%d",t);
}
printf("\n");
}
return 0;
}