Compilare: user.cpp: In function ‘void sol()’: user.cpp:28:80: warning: statement has no effect [-Wunused-value] if(G[i].empty()) {int v; v=s[nrs-1]-'0'; v++; f[i]=v; s[nrs]=v+'0'; s[nrs+1]; fprintf(g1,"%d ",v); } ^ user.cpp:39:91: warning: converting to non-pointer type ‘char’ from NULL [-Wconversion-null] if(strchr(s,c)==NULL) {f[i]=p;fprintf(g1,"%d ",p); nrs++; s[nrs-1]=c; s[nrs]=NULL;} ^ user.cpp:45:85: warning: converting to non-pointer type ‘char’ from NULL [-Wconversion-null] if(strchr(s,c)==NULL) {f[i]=p; fprintf(g1,"%d ",p); nrs++; s[nrs-1]=c; s[nrs]=NULL;} ^ user.cpp: In function ‘void read()’: user.cpp:17:25: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f1,"%d%d",&n,&m); ^ user.cpp:19:26: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] {fscanf(f1,"%d%d",&x,&y); ^