Compilare: user.cpp: In function ‘std::vector<int> Merge(std::vector<int>, std::vector<int>)’: user.cpp:13:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<=a.size();i++) ^ user.cpp:14:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=0;j<=b.size();j++) ^ user.cpp:17:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=1;i<=a.size();i++){ ^ user.cpp:21:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=1;i<=b.size();i++){ ^ user.cpp:25:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<=a.size();i++) ^ user.cpp:26:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=0;j<=b.size();j++){ ^ user.cpp:27:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(i<a.size()&&dp[i][j]+sum-suma[i+1]-sumb[j]<dp[i+1][j]){ ^ user.cpp:31:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(j<b.size()&&dp[i][j]+sum-suma[i]-sumb[j+1]<dp[i][j+1]){ ^ user.cpp: In function ‘void DFS(int)’: user.cpp:55:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<g[node].size();i++){ ^ user.cpp: In function ‘int main()’: user.cpp:75:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=1;i<order[0].size();i++) ^ user.cpp:62:41: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("purification.in","r",stdin); ^ user.cpp:63:43: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("purification.out","w",stdout); ^ user.cpp:66:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&n); ^ user.cpp:68:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&cost[i]); ^ user.cpp:70:23: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&x); ^