Can Kelly solve enough code challenges to catch up with Sam?

Sam and Kelly are programming buddies. Kelly resolves to practice more as Sam is ahead initially. They each solve a number of problems daily. Find the minimum number of days for Kelly to have solved more problems than Sam. If Kelly cannot surpass return -1.

Example

samDaily = 3

kellyDaily = 5

difference = 5

Initially, Sam has solved difference problems more than Kelly. Each day, they solve samDaily and kellyDaily problems each.

Day 1: samSolved = difference + samDaily = 5 + 3 = 8

_            kellySolved_ = _kellyDaily = _5

Day 2: samSolved = 8 + 3 = 11

_            kellySolved_ = 5 + 5 = 10

Day 3: samSolved = 11 + 3 = 14

_            kellySolved_ = 10 + 5 = 15

Sam is 5 problems ahead of Kelly and they solve 3 and 5 problems a day. Sam will be ahead by only 3 after the first day, 1 after the second, and Kelly will pass Sam on day 3.

**Function Description **

Complete the function minNum in the editor below.

minNum has the following parameter(s):

    samDaily:  Number of problems Sam solves in a day

    kellyDaily:  Number of problems Kelly solves in a day

    difference_:_  Number of problems Sam is ahead to begin

Return

    _int: _the minimum number of days needed by Kelly to exceed Sam, or -1 if it is impossible

Constraints

• 1 ≤ samDaily, kellyDaily ≤ 100

• 0 ≤ difference ≤ 100

  Input Format For Custom Testing

Input from stdin will be processed as follows and passed to the function.

The first line contains an integer samDaily.

The second line contains an integer kellyDaily.

The third line contains an integer ahead.

Sample Case 0

Sample Input 0

STDIN     Function -----     -------- 3    →    samDaily = 3 5    →    kellyDaily = 5 1    →    difference = 1

Sample Output 0

1

Explanation 0

Sam is 1 problem ahead of Kelly to begin. After 1 day passes, Kelly will have solved 5 problems while Sam will have only solved 1 + 3 = 4 problems.

Sample Case 1

Sample Input 1

STDIN     Function -----     -------- 4    →    samDaily = 4 5    →    kellyDaily = 5 1    →    difference = 1

Sample Output 1 

2

Explanation 1

Sam is 1 problem ahead of Kelly to begin. After 1 day passes, Kelly will have solved 5 problems while Sam will have also solved 1 + 4 = 5 problems. On the second day, Kelly will surpass Sam, 5 + 5 > 1 + 4 + 4.