---

import sys

def main():
    data = sys.stdin.read().split()
    if not data:
        return
    K = int(data[0])
    M = int(data[1])
    A = int(data[2])
    B = int(data[3])
    
    result = (B // K - (A - 1) // K) - (B // M - (A - 1) // M)
    print(result)

if __name__ == '__main__':
    main()