Codeforces Round #324 (Div. 2) A. Olesya and Rodion 水题

A. Olesya and Rodion

Time Limit: 1 Sec  

Memory Limit: 256 MB

题目连接

http://codeforces.com/contest/584/problem/A

Description

Olesya loves numbers consisting of n digits, and Rodion only likes numbers that are divisible by t. 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 and t (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

3 2

Sample Output

712

HINT

题意

让你构造一个数，使得这个数有n位，且mod k==0；

题解：

只有一个情况输出-1，就是10 1的时候

其他情况，就直接在后面加0就好了

比如 3 2

你就输出 300

4 7

你就输出 4000000

代码：

#include<stdio.h>
#include<iostream>
#include<math.h>

using namespace std;

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