Compilare: user.cpp: In function ‘int main()’: user.cpp:29:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(r + pas < stk[x].size() && (stk[x][stk[x].size() - 1 - r - pas].second <= val + 1)) ~~~~~~~~^~~~~~~~~~~~~~~ user.cpp:16:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("mate.in", "r", stdin); ^ user.cpp:17:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("mate.out", "w",stdout); ^