---

import sys
import math

def solve():
    
    input_data = sys.stdin.read().split()
    if not input_data:
        return
    
    v = int(input_data[0])
    a = int(input_data[1])
    b = int(input_data[2])
    n = int(input_data[3])
    
    MODULO = 10**18

   
    count_in = n // a
    count_out = n // b

   
    gcd_ab = math.gcd(a, b)
    lcm_ab = (a // gcd_ab) * b

    ans = v + count_in - count_out

    print(ans % MODULO)

if __name__ == '__main__':
    solve()