petrol.cpp: In function 'int main()': petrol.cpp:7: warning: unused variable 's' petrol.cpp:4: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result petrol.cpp:5: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result petrol.cpp:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result petrol.cpp:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result petrol.cpp:6: warning: 'pe1' may be used uninitialized in this function petrol.cpp:6: warning: 'pd1' may be used uninitialized in this function