A. Olesya and Rodion
time limit per test
1 secondmemory limit per test
256 megabytesinput
standard inputoutput
standard outputOlesya 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.
Examples
Input
3 2
Output
712
题意; 输出一个数 长度为n并且为t的倍数 不存在 则输出-1
题解: n个t 组成的数一定是t的倍数
考虑特殊 t=10的情况 (水)
1 #include<iostream> 2 #include<cstring> 3 #include<cstdio> 4 #include<queue> 5 #include<stack> 6 #include<cmath> 7 #define ll __int64 8 #define pi acos(-1.0) 9 #define mod 1000000007 10 using namespace std; 11 int n,t; 12 int main() 13 { 14 scanf("%d %d",&n,&t); 15 if(t<10) 16 { 17 for(int i=1;i<=n;i++) 18 printf("%d",t); 19 cout<<endl; 20 } 21 if(t==10) 22 { 23 if(n==1) 24 cout<<"-1"<<endl; 25 else 26 { 27 for(int i=1;i<n;i++) 28 printf("1",t); 29 cout<<"0"<<endl; 30 } 31 } 32 return 0; 33 }