foo.cc: In function ‘int main()’:
foo.cc:6:16: error: expected ‘;’ before ‘for’
    6 |         cin>>gs
      |                ^
      |                ;
    7 |         for(i=1;i<=gs;i++)
      |         ~~~     
foo.cc:7:18: warning: statement has no effect [-Wunused-value]
    7 |         for(i=1;i<=gs;i++)
      |                 ~^~~~
foo.cc:7:26: error: expected ‘;’ before ‘)’ token
    7 |         for(i=1;i<=gs;i++)
      |                          ^
      |                          ;