Main.c: In function 'su':
Main.c:8:5: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'else'
    8 |     else{
      |     ^~~~
Main.c:8:5: error: 'else' without a previous 'if'
Main.c:10:13: error: 'rw' undeclared (first use in this function)
   10 |             rw=(r+1)/2;
      |             ^~
Main.c:10:13: note: each undeclared identifier is reported only once for each function it appears in
Main.c:10:17: error: 'r' undeclared (first use in this function)
   10 |             rw=(r+1)/2;
      |                 ^
Main.c:11:13: error: 'rz' undeclared (first use in this function)
   11 |             rz=(r-1)/2;
      |             ^~
Main.c:18:5: error: 'sz' undeclared (first use in this function); did you mean 'su'?
   18 |     sz=2*rz;
      |     ^~
      |     su
Main.c:3:11: warning: unused variable 'd' [-Wunused-variable]
    3 |     int i,d=0;
      |           ^