#include <stdio.h>
#include <iso646.h>

int main(void) {
    unsigned long long int x, y, z, count = 0;
    scanf("%lld %lld %lld", &x, &y, &z);
    for (int i = 1; i <= z; i++) {
        if (i == x or i == y) continue;
        count++;
    }
    printf("%lld\n", count);
    return 0;
}