#include <stdio.h>
int sum(int n)
{
if (n==0)
return 0;
return n + sum(n - 1);
}
int main()
{
int n;
return 0;
}
I2luY2x1ZGUgPHN0ZGlvLmg+CgppbnQgc3VtKGludCBuKQp7CiAgICBpZiAobj09MCkKICAgICAgICByZXR1cm4gMDsKICAgIHJldHVybiBuICsgc3VtKG4gLSAxKTsKfQoKaW50IG1haW4oKQp7CiAgICBpbnQgbjsKICAgIHNjYW5mKCIlZCIsICZuKTsKCiAgICBwcmludGYoIiVkXG4iLCBzdW0obikpOwoKICAgIHJldHVybiAwOwp9Cgo=