#include<iostream> #include<cmath> #include<cstdio> using namespace std; int main() { int n; cin >> n; int a, b, c; a = 1; b = 2; c = 3; double y, sum=0; for (int i = 0; i < n; i++) { y = (double)b / a; c = b; b = a + b; a = c; sum = sum + y; } printf("%.6lf", sum); return 0; } |
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