Barnicle, C++ (gcc)

Language: Layout:

#include <bits/stdc++.h>
using namespace std;

#define f(i,n) for(int i = 0; i < n; i++)
#define ll long long
#define pii pair<int, int>
#define pll pair<ll, ll>
#define vi vector<int>
#define vl vector<ll>
#define vii vector<pii>
#define vll vector<pll>
#define vvi vector<vi>
#define vvl vector<vl>
#define inf INT_MAX
#define llinf LONG_LONG_MAX
#define F first
#define S second
#define pb push_back
#define fast ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define int long long

void solve() {
    string s;
    cin >> s;
    int n = s.length();
    int decimal = 0;
    for(int i = n - 1; i >= 0; i--) {
        if(s[i] <= '9' && s[i] >= '0') {
            decimal *= 10;
            decimal += s[i] - '0';
        } else {
            break;
        }
    }
    cout << s[0];
    int k = 0;
    for(int i = 2; i < 2 + decimal; i++) {
        cout << s[i];
        if(s[i] == 'e') {
            k = 1;
        }
    }
    if(s[2 + decimal] != 'e') {
        cout << ".";
        for(int i = 2 + decimal; i < n; i++) {
            if(s[i] == 'e') {
                break;
            } else {
                cout << s[i];
            }
        }
    }
}

signed main() {
    fast;
    int t = 1;
    //cin >> t;
    while(t--) {
        solve();
    }
    return 0;
}

Show compiler warnings [ + ] Compiler args [ - ] Show input
Compilation time: 1.53 sec, absolute running time: 0.19 sec, cpu time: 0 sec, memory peak: 3 Mb, absolute service time: 1,86 sec