C++ :

#include <algorithm>
#include <cstdio>

using namespace std;

int days[20] = {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};

int main() {
    int m;
    scanf("%d", &m);
    printf("MON TUE WED THU FRI SAT SUN\n");
    int d = days[m];

    int w = 1;
    if (m > 9) {
        for (int i = 9; i < m; i++) w = (w + days[i] - 1) % 7 + 1;
    } else if (m < 9) {
        for (int i = 8; i >= m; i--) w = ((w - days[i]) % 7 + 7) % 7;
        if (w == 0) w = 7;
    }

    for (int i = 1; i < w; i++) printf("   ");
    for (int i = 1; i <= d; i++) {
        printf("% 3d", i);
        w = w % 7 + 1;
        if (w == 1 || i == d)
            printf("\n");
        else
            printf(" ");
    }
    return 0;
}