address
int fib(int n){ if(n == 0) return 0; if(n == 1) return 1; int a[n+1]; a[0] = 0; a[1] = 1; for(int i = 2; i<=n; i++) a[i] = (a[i-1] + a[i-2])%1000000007; return a[n]; }