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;}