C :

#include <stdio.h>
double a, b;
int main(void) {
    scanf("%lf %lf", &a, &b);
    if (a > 0 && b > 0) {
        printf("%.2f %.2f", a * b, 2.0 * (a + b));
    } else {
        printf("error");
    }
    printf("\n");
    return 0;
}

C++ :

#include<iostream>

#include<cstdio>

using namespace std;

int main()
{
    double a,b;
    cin>>a>>b;
    if (a>0&&b>0)
    printf("%.2lf %.2lf",a*b,(a+b)*2);
else
    cout<<"error"<<endl;
    return 0;
}

Python :

# coding=utf-8
s = input(). split()
a, b = float(s[0]), float(s[1])
if a > 0 and b > 0 :
    print(format(a * b, ".2f"), format(2 * (a + b), ".2f"))
else :
    print("error")