752 B | 752 chars
import sys
from math import sqrt, pi, sin, factorial, ceil, floor
from datetime import datetime, timedelta
BLANK = " "
# inp = input
inp = lambda : sys.stdin.readline()[:-1].strip()
mii = lambda x = BLANK : [*map(int,inp().split(x))]
mfi = lambda x = BLANK : [*map(float,inp().split(x))]
ii = lambda : int(inp())
fi = lambda : float(inp())
p = print
def f(num):
d = 1
while d < num:
d *= 2
return d
def solve():
while 1:
G, T, A, D = mii()
if G == T == A == D == -1:
break
z = A * G + D
z2 = f(z)
Y = z2 - z
X = z2 - 1 + (T * (T - 1) * G // 2)
p(f"{G}*{A}/{T}+{D}={X}+{Y}")
if __name__ == "__main__":
tc = 1
for t in range(1, tc+1):
ret = solve()