Compilare: user.c: In function ‘mergee’: user.c:23:20: warning: operation on ‘a’ may be undefined [-Wsequence-point] if(P[a]<P[b]) a^=b^=a^=b; ^ user.c: In function ‘main’: user.c:33:5: warning: implicit declaration of function ‘malloc’ [-Wimplicit-function-declaration] par=(int*)malloc((n)*sizeof(int)); ^ user.c:33:15: warning: incompatible implicit declaration of built-in function ‘malloc’ [enabled by default] par=(int*)malloc((n)*sizeof(int)); ^ user.c:38:5: warning: implicit declaration of function ‘qsort’ [-Wimplicit-function-declaration] qsort(t,m,sizeof(el),cmp); ^ user.c:30:12: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("apm.in","r",stdin); ^ user.c:31:12: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("apm.out","w",stdout); ^ user.c:32:10: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&n,&m); ^ user.c:36:20: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] fr(i,0,m) scanf("%d%d%d",&t[i].fp,&t[i].ep,&t[i].s),--t[i].fp,--t[i].ep; ^