C++NO1

#include<bits/stdc++.h>
using namespace std;
int main(){
    double n,ans; cin >> n;
    string s; cin >> s;
    if(s == "in") ans = 2.54 * n;
    else{
        if(n != 0 && s == "cm") ans = n / 2.54;
        else{
            cout << "error";
            return 0;
        }
    }
    printf("%.2lf",ans);
    if(s == "in") cout << " cm";
    else cout << " in";
    return 0;
}