foo.cc:2:1: error: 'usin' does not name a type
    2 | usin namespace std;
      | ^~~~
foo.cc: In function 'int main()':
foo.cc:10:9: error: 'm0' was not declared in this scope; did you mean 'm'?
   10 |    if(a%m0)
      |         ^~
      |         m
foo.cc:9:3: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
    9 |   for(m=2;m<=a/2;m++)
      |   ^~~
foo.cc:12:4: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'for'
   12 |    if(m>a/2)
      |    ^~
foo.cc:17:10: error: 'k0' was not declared in this scope; did you mean 'k'?
   17 |     if(b%k0)
      |          ^~
      |          k
foo.cc:16:4: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
   16 |    for(k=2;k<=b/2;k++)
      |    ^~~
foo.cc:19:5: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'for'
   19 |     if(k>b/2)
      |     ^~
foo.cc:6:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
    6 |  scanf("%d",&n);
      |  ~~~~~^~~~~~~~~

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