#include <stdio.h>

int main(void) {
    char color;

    printf("What is the color of you cylinder? ");
    scanf("%c", &color);

    switch (color) {
        case 'o':
        case 'O':
            printf("ammonia\n");
            break;
        case 'b':
        case 'B':
            printf("carbon monoxide\n");
            break;
        case 'y':
        case 'Y':
            printf("hydrogen\n");
            break;
        case 'g':
        case 'G':
            printf("Oxygen\n");
            break;
        default:
            printf("Contents unknown\n");
    } //switch
    return 0;
} //main