foo.cc: In function 'int main()':
foo.cc:61:19: warning: unused variable 'j' [-Wunused-variable]
   61 |         int n,m,i,j,t1,len;
      |                   ^
foo.cc:61:24: warning: variable 'len' set but not used [-Wunused-but-set-variable]
   61 |         int n,m,i,j,t1,len;
      |                        ^~~

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