Give the output on the screen of the following program (indicate a space using this symbol _):

#include<stdio.h>
double mystery(int T[], int i)
{
     int k;
     for(k=0 ; k<i ; k++)
          T[k] -= T[i] - k;
     return T[k] + 1;
}
int main()
{
     int a = 7, b = 4, c, T[] = {4,-4,8,0};
     double x = 0.02, y = -0.05, z = 0.1 ;
     c = 1;
     for (a = 0; a < 5; a++)
     {
          for (b = a; b < 5; b++)
               switch (a-b) {
                    case 0:
                    case 2:
                    case 4: c++;
                    case 6: break;
                    case 8: c--;
                    case 12:
                    default: c++;
               }
          printf("#%d# %d ##\n", 12 + a , c);
     }
     printf("#17# %0.0lf ##\n", mystery(T, 2));
     printf("#18# %d ##\n", T[0]);
     printf("#19# %d ##\n", T[0%4]);
     printf("#20# %d ##\n", -T[0]%3);
     return 0;
}

Difficulty level
This exercise is mostly suitable for students 
#12# 6 ##
#13# 10 ##
#14# 13 ##
#15# 15 ##
#16# 16 ##
#17# 9 ##
#18# -4 ##
#19# -4 ##
#20# 1 ##
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