foo.c: In function 'main':
foo.c:7:12: warning: statement with no effect [-Wunused-value]
    7 |         x>1&&x<100;
      |         ~~~^~~~~~~
foo.c:8:14: error: invalid suffix "n" on integer constant
    8 |         if(x=2n-1)
      |              ^~
foo.c:9:17: error: 'next' undeclared (first use in this function)
    9 |                 next=3x+1;
      |                 ^~~~
foo.c:9:17: note: each undeclared identifier is reported only once for each function it appears in
foo.c:9:22: error: invalid suffix "x" on integer constant
    9 |                 next=3x+1;
      |                      ^~
foo.c:10:14: error: invalid suffix "n" on integer constant
   10 |         if(x=2n)
      |              ^~
foo.c:5:8: warning: unused variable 'n' [-Wunused-variable]
    5 |  int x,n,s;
      |        ^

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