camp.cpp: In function 'int main()': camp.cpp:133: warning: unused variable 'u' camp.cpp:133: warning: unused variable 'v' camp.cpp:133: warning: unused variable 't' camp.cpp:131: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result camp.cpp:132: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result camp.cpp:134: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result camp.cpp:137: warning: ignoring return value of 'char* gets(char*)', declared with attribute warn_unused_result In file included from /usr/include/stdio.h:910, from /usr/include/c++/4.4/cstdio:45, from camp.cpp:1: In function 'char* gets(char*)', inlined from 'int main()' at camp.cpp:137: /usr/include/bits/stdio2.h:230: warning: call to '__gets_warn' declared with attribute warning: please use fgets or getline instead, gets can't specify buffer size /tmp/ccI5zGPh.o: In function `main': camp.cpp:(.text+0x7a5): warning: the `gets' function is dangerous and should not be used.