foo.cc: In function 'int main()':
foo.cc:15:36: warning: unused variable 'n' [-Wunused-variable]
   15 |         int a[100005]={0,1},len1=1,n,b[100005]={0,1},len2=1,c[100005],x1,x2,m1,m2,len;
      |                                    ^

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