View Compilation Error

0_0_13217091_30961.cpp: In function 'int main()':
0_0_13217091_30961.cpp:86:38: error: 'scanf' was not declared in this scope
    while(scanf("%d%d%d%d",&n,&m,&x,&p)!=EOF)
                                      ^
0_0_13217091_30961.cpp:86:41: error: 'EOF' was not declared in this scope
    while(scanf("%d%d%d%d",&n,&m,&x,&p)!=EOF)
                                         ^
0_0_13217091_30961.cpp:96:30: error: 'sort' was not declared in this scope
       sort(seg+1,seg+1+n,cmp1);
                              ^
0_0_13217091_30961.cpp:125:25: error: 'printf' was not declared in this scope
             printf("0\n");
                         ^
0_0_13217091_30961.cpp:147:28: error: 'printf' was not declared in this scope
         printf("%lld\n",pre);
                            ^