#include <stdio.h>

int main() {
    int age;
    printf("Enter age:");
    scanf("%d", &age);
    
    if (age < 0) {
        printf("Invalid input\n");
    } else if (age >= 18)
        printf("Eligible\n");
    else
        printf("Not eligible\n");
    }
    
    
    return 0;