Problem:
Score : 300 points

Problem Statement

Takahashi loves the number 7 and multiples of K.

Where is the first occurrence of a multiple of K in the sequence 7,77,777,\ldots? (Also see Output and Sample Input/Output below.)

If the sequence contains no multiples of K, print -1 instead.

Constraints

1 \leq K \leq 10^6

K is an integer.

Input

Input is given from Standard Input in the following format:

K

Output

Print an integer representing the position of the first occurrence of a multiple of K. (For example, if the first occurrence is the fourth element of the sequence, print 4.)

Sample Input 1

101

Sample Output 1

4

None of 7, 77, and 777 is a multiple of 101, but 7777 is.

Sample Input 2

2

Sample Output 2

-1

All elements in the sequence are odd numbers; there are no multiples of 2.

Sample Input 3

999983

Sample Output 3

999982

Solution in JavaScript (Node.js 12.16.1) (judge verdict: Time Limit Exceeded)

function Main(input) {
  
  input = Number(input)
  
  let output = -1 
  let temp_number777;
  
  if(input%2===0){
  
  }else{
  
   	for(let i=1;;i++){
      	temp_number777 = ""
      for(let g=1;g<=i;g++){
      	temp_number777 += "7"
      }
      temp_number777 = Number(temp_number777)
      
       if(temp_number777%input === 0){
       		output = i
         	break;
       }

    }
  
  }

  	console.log(output)
    
}
Main(require("fs").readFileSync("/dev/stdin", "utf8"));