#include<cstdio>
int main()
{
int a, b ,n, num=0;
scanf("%d%d%d", &a, &b, &n);
for(int x=0; x<=a; x++)
{
for(int y=0; y<=b; y++)
{
if (x+y == n) num += 1;
}
}
printf("%d\n", num);
return 0;
}
# python 代码
a = int(input())
b = int(input())
n = int(input())
num = 0
for x in range(a+1):
for y in range(b+1):
if x + y == n:
num += 1
print(num)