Compilare: user.cpp: In function ‘int binary_search2(int, int, int)’: user.cpp:15:44: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (step = 1; step < mat[x0][y0].size(); step <<= 1); ^ user.cpp:17:41: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (i + step < mat[x0][y0].size() && mat[x0][y0][i + step] <= valsec) ^ user.cpp: In function ‘int main()’: user.cpp:59:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(nr == stiva.size()) ^ user.cpp:73:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(nr+1 == stiva.size())stiva.pop_back(); ^ user.cpp:24:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("search.in","r",stdin); ^ user.cpp:25:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("search.out","w",stdout); ^ user.cpp:26:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d ",&n,&m); ^ user.cpp:32:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%c",&x); ^ user.cpp:44:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%c ",&x); ^