foo.cpp: In function 'int cal(std::string, int, int, int)':
foo.cpp:40:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
foo.cpp:67:39: error: 'abs' was not declared in this scope
foo.cpp:80:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
foo.cpp:106:40: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
foo.cpp: In function 'int main()':
foo.cpp:169:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
foo.cpp:200:40: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]