Problem:
Score : 200 points

Problem Statement

Takahashi's house has only one socket.

Takahashi wants to extend it with some number of power strips, each with A sockets, into B or more empty sockets.

One power strip with A sockets can extend one empty socket into A empty sockets.

Find the minimum number of power strips required.

Constraints

All values in input are integers.

2 \leq A \leq 20

1 \leq B \leq 20

Input

Input is given from Standard Input in the following format:

A B

Output

Print the minimum number of power strips required.

Sample Input 1

4 10

Sample Output 1

3

3 power strips, each with 4 sockets, extend the socket into 10 empty sockets.

Sample Input 2

8 9

Sample Output 2

2

2 power strips, each with 8 sockets, extend the socket into 15 empty sockets.

Sample Input 3

8 8

Sample Output 3

1

Solution in C (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
int gcd(int a,int b);
int compare(const void* a, const void* b);

int main(void){
    int A,B;
    int i = 1;
    int ret = 0;
    scanf("%d %d",&A,&B);
    while(i < B){
        i = i + A; //1口つかってA口ふやす
        ret++;
        if(i>=B){
            break;
        }else{
            i--;
        }
    }
    printf("%d\n",ret);    
}
int compare(const void* a, const void* b){
    return strcmp(a, b);
}
// 最大公約数
int gcd(int a,int b){
    int c;
    int tmp;
    if(b > a){  //bがaより大きい場合bとaを入れ替える
        c = a;
        a = b;
        b = c;
    }
    tmp = a % b;
    while(tmp!=0){
        a = b;
        b = tmp;
        tmp = a % b;
    }
    return b;
}