foo.cc: In function 'int main()':
foo.cc:11:19: error: 'strlen' was not declared in this scope
   11 |         if (si <= strlen(s))
      |                   ^~~~~~
foo.cc:2:1: note: 'strlen' is defined in header '<cstring>'; did you forget to '#include <cstring>'?
    1 | #include<iostream>
  +++ |+#include <cstring>
    2 | using namespace std;
foo.cc:34:30: error: 'strlen' was not declared in this scope
   34 |         for (long j = 0; j < strlen(s); j++)
      |                              ^~~~~~
foo.cc:34:30: note: 'strlen' is defined in header '<cstring>'; did you forget to '#include <cstring>'?
foo.cc:7:15: warning: unused variable 'S' [-Wunused-variable]
    7 |         char* S = s;
      |               ^

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