#include<cstdio> #include<cstdlib> #include<cmath> #include<iostream> #include<algorithm> using namespace std; int main(){ float a=2,b=1,sum=2; int n; scanf("%d",&n); for(int i=1;i<n;i++) { float t=a; float v=b; a=a+b; b=t; sum+=a/b; } printf("%.2f\n",sum); return 0; } |
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