Euclid's Algorithm(Recursive) to compute GCD

#include <stdio.h>
int gcd(int a, int b){
    if (!b) return a; //if b is less than 1, return a
    else return gcd(b, a % b); // if b is positive, call the function again
}
int main(){
    int a, b;
    printf("Enter two integers: ");
    scanf("%d%d", &a, &b);
    printf("The GCD is %d.", gcd(a,b));
}