Program that using a function that zodiac sign is according to the day and month of birth

#include <stdio.h>
int main()
{
    int month, day, sign;
    printf("Enter the month and day of your birth:");
    scanf("%d%d", &month, &day);
    if (month == 3) {
        if (day >= 21)
            sign = 1;
        else
            sign = 0;
    }
    if (month == 4) {
        if (day >= 21)
            sign = 2;
        else
            sign = 1;
    }
    if (month == 5) {
        if (day >= 21)
            sign = 3;
        else
            sign = 2;
    }
    if (month == 6) {
        if (day >= 22)
            sign = 4;
        else
            sign = 3;
    }
    if (month == 7) {
        if (day >= 23)
            sign = 5;
        else
            sign = 4;
    }
    if (month == 8) {
        if (day >= 23)
            sign