medium level problem - Marbles SIGSEGV error

for the problem Marbles : http://www.codechef.com/problems/MARBLES here is the code. But the problem is code chef is returning SIGSEGV error and i am unable to find out the problem in my code. So please tell me can my code be modified to fit the conditions of the question or do i have to think from a new perspective?

here is the code:

#include<iostream>
using namespace std;

long long int C(int n,int r)
{
    if(r==1)
        return n;
    if(n==r)
        return 1;
    long long int c=C(n-1,r)+C(n-1,r-1);
    return c;
}

int main()
{
    int t;
    cin>>t;
    while(t--)
    {
        int n,r;
        cin>>n>>r;
        cout<<C(n-1,r-1)<<endl;
    }
}