foo.cc: In function 'int main()':
foo.cc:7:10: warning: unused variable 'a' [-Wunused-variable]
    7 |  int n,m,a,b,c,s1,s2,s3,i;
      |          ^
foo.cc:7:12: warning: unused variable 'b' [-Wunused-variable]
    7 |  int n,m,a,b,c,s1,s2,s3,i;
      |            ^
foo.cc:7:14: warning: unused variable 'c' [-Wunused-variable]
    7 |  int n,m,a,b,c,s1,s2,s3,i;
      |              ^
foo.cc:7:19: warning: variable 's2' set but not used [-Wunused-but-set-variable]
    7 |  int n,m,a,b,c,s1,s2,s3,i;
      |                   ^~
foo.cc:7:22: warning: variable 's3' set but not used [-Wunused-but-set-variable]
    7 |  int n,m,a,b,c,s1,s2,s3,i;
      |                      ^~

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