G - Gibonacci number

http://acm.hust.edu.cn/vjudge/contest/view.action?cid=23407#problem/G

#include <stdio.h>

int test;
long long i,gi,j,t;
int k,l;
long long fib[21];

int main() {
	fib[0]=0;fib[1]=1;
	for (k=2;k<=20;k++) fib[k]=fib[k-2]+fib[k-1];
	scanf("%d",&test);
	for (k=1;k<=test;k++) {
		scanf("%lld%lld%lld",&i,&gi,&j);
		if ((gi-fib[i-1])%fib[i]!=0) printf("-1\n");
		else {
			t=(gi-fib[i-1])/fib[i];
			if (t<1) printf("-1\n");
			else printf("%lld\n",fib[j-1]+fib[j]*t);
		}
	}
	return 0;
}