1176 The Closest Fibonacci Number

#include<iostream>
#include<cmath>
using namespace std;
int main(){
int n,fn,fn_1=1,fn_2=1;
cin>>n;
for(int i=2;;i++){
fn=fn_1+fn_2;
if(abs(fn-n)>=abs(fn_1-n)){
cout<<fn_1<<endl;
return 0;
}
fn_2=fn_1;
fn_1=fn;
}
return 0;
}