#include <stdio.h>

void buildingFootprint(void) {
    double electricityKWh;
    printf("\n[Building] Enter monthly electricity consumption (kWh): ");
    scanf("%lf", &electricityKWh);
    printf("Building Annual Carbon Footprint: %.2f kg CO2\n", electricityKWh * 12 * 0.4);
}

void carFootprint(void) {
    double miles;
    printf("\n[Car] Enter annual miles driven: ");
    scanf("%lf", &miles);
    printf("Car Annual Carbon Footprint: %.2f kg CO2\n", miles * 0.404);
}

void bicycleFootprint(void) {
    puts("\n[Bicycle] Direct operational emissions: 0.00 kg CO2 (Eco-friendly).");
}

int main(void) {
    void (*footprintCalculators[3])(void) = {buildingFootprint, carFootprint, bicycleFootprint};
    int choice;

    printf("Calculate Carbon Footprint for:\n"
           "0: Building\n1: Car\n2: Bicycle\nEnter choice: ");
    scanf("%d", &choice);

    if (choice >= 0 && choice <= 2) {
        (*footprintCalculators[choice])();
    } else {
        puts("Invalid selection.");
    }
    return 0;
}