#include <bits/stdc++.h> using namespace std; int main() { double a[999]; double b[999]; double f[999]; f[0]=1.0; f[1]=2.0; for(int i=2;i<999;i++) { f[i]=f[i-1]+f[i-2]; } int n; cin>>n; b[0]=0; for(int i=1;i<=n;i++) { a[i]=f[i]/f[i-1]; b[i]=b[i-1]+a[i]; } printf("%.2lf",b[n]); return 0; } |
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