primo.c

#include <stdio.h>

char * isprimo(int number) {
    int i, ndiv = 0;

    for(i = 1; i <= number; i++) {
        if((number % i) == 0)
            ndiv++;
    }

    return ((ndiv == 2) ? "sim" : "nao");
}

int main() {
    int num;
    scanf("%d", &num);

    printf("%s", isprimo(num));

    return 0;
}