Compilare: main.cpp: In function 'int main()': main.cpp:30:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < s.size(); ++i) { ~~^~~~~~~~~~ main.cpp:32:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(i + k < s.size() && i - k >= 0 && s[i+k] == s[i-k]) ++k; ~~~~~~^~~~~~~~~~ main.cpp:9:35: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("pscpld.in", "r", stdin); ^ main.cpp:10:37: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("pscpld.out", "w", stdout); ^