#include<stdio.h>
int main(){
    int month;
    scanf("%d",&month);
    if(month<1||month>15)
    {
        printf("Invalid input\n");
        return 0;
    }
    switch(month)
    {
        case 1:
        case 3:
        case 5:
        case 7:
        case 8:
        case 10:
        case 12:
        printf("31\n");
        break;
        case 4:
        case 6:
        case 9:
        case 11:
        printf("30\n");
        break;
        case 2:
        printf("28 or 29\n");
        default:
        printf("Invalid input\n");
        break;
    }
    return 0;
}
        
    }
}