580 B | 580 chars
import sys
from math import sqrt, pi, sin, factorial
inp = lambda : sys.stdin.readline()[:-1].strip()
mii = lambda x = " " : [*map(int,inp().split(x))]
mfi = lambda x = " " : [*map(float,inp().split(x))]
ii = lambda : int(inp())
fi = lambda : float(inp())
p = print
def solve():
a, b, c = mii()
s = set()
for i in range(c + 1):
for j in range(0, c - i + 1):
k = c - i - j
if a + i <= b + j:
continue
s.add((a + i, b + j, k))
print(len(s))
if __name__ == "__main__":
tc = 1
for t in range(1, tc+1):
solve()