Compilare: main.cpp: In function 'bool ok(int)': main.cpp:106:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int k1 = 0; k1 < vec.size(); k1++) { ~~~^~~~~~~~~~~~ main.cpp:107:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int k2 = k1 + 1; k2 < vec.size(); k2++) { ~~~^~~~~~~~~~~~ main.cpp: In function 'char read_ch()': main.cpp:22:35: warning: ignoring return value of 'size_t fread(void*, size_t, size_t, FILE*)', declared with attribute warn_unused_result [-Wunused-result] fread(_in_buff, 1, 4096, _fin); ^ main.cpp: In function 'int main()': main.cpp:121:39: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("robotics.out", "w", stdout); ^