#include<stdio.h>

typedef enum {MON, TUE, WED, THU, FRI, SAT, SUN} DayType;

DayType nextDay(DayType day) {
  return (day+1) % 7;
}

void printDay(DayType day) {
  switch(day) {
  case MON: printf("monday"); break;
  case TUE: printf("tuesday"); break;
  case WED: printf("wednesday"); break;
  case THU: printf("thursday"); break;
  case FRI: printf("friday"); break;
  case SAT: printf("saturday"); break;
  case SUN: printf("sunday"); break;
  }
  printf("\n");
}

int main() {
  DayType day;
  day = SUN;
  printDay(day);
  printDay(nextDay(day));
}