class Solution:
    def solve(self, n:int) -> int:
        print(f"n: {n}")
        '''
        find how many (a, b) are possible where a + b = n
        n = 3 -> (1, 2), (2, 1)
        n = 4 -> (1, 3), (2, 2), (3, 1)
        '''
        a = 1       
        count = 0
        while n - a > 0:  
            a += 1
            count += 1
        return count
    
s = Solution()
print(s.solve(3))  # Output: 2
print(s.solve(4))  # Output: 3  
print(s.solve(5))  # Output: 4