Compilare: user.cpp: In function ‘int main()’: user.cpp:4:92: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("sortnet.in","r",stdin),freopen("sortnet.out","w",stdout),scanf("%d%d\n",&n,&m); ^ user.cpp:4:92: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] user.cpp:4:92: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] user.cpp:7:60: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("<%d,%d> ",&a,&b),a--,b--,g[i][a]=b,g[i][b]=a; ^