/in/foo.cc: In function 'int main()':
/in/foo.cc:7:13: warning: unused variable 'b' [-Wunused-variable]
     int n,a,b,c,s1,s2,s3,i;
             ^
/in/foo.cc:7:15: warning: unused variable 'c' [-Wunused-variable]
     int n,a,b,c,s1,s2,s3,i;
               ^
/in/foo.cc:7:20: warning: unused variable 's2' [-Wunused-variable]
     int n,a,b,c,s1,s2,s3,i;
                    ^~
/in/foo.cc:7:23: warning: unused variable 's3' [-Wunused-variable]
     int n,a,b,c,s1,s2,s3,i;
                       ^~