Compilare: user.cpp: In function ‘void upd(int, int, int, int&, int&)’: user.cpp:32:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (i >= a[cuv].size()) cost += abs('@' , b[j]); ^ user.cpp: In function ‘int main()’: user.cpp:48:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("dist.in","r",stdin); ^ user.cpp:49:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("dist.out","w",stdout); ^ user.cpp:51:12: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(s); a.push_back(" "); ^ user.cpp:55:12: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(s); int pos = 0, np = 0; b = " "; ^ /tmp/cc2wxtSH.o: In function `main': user.cpp:(.text.startup+0x56): warning: the `gets' function is dangerous and should not be used.