import sys
input = sys.stdin.readline
sys.setrecursionlimit(2147483647)
INF=float("inf")
MOD=10**9+7
# A = [ int(input()) for _ in range(N) ]
##############################

X, Y, Z = map(int, input().split())
ans = 0
for i in range(1, Z+1):
    if i == X or i == Y:
        continue

    ans += 1

print(ans)