View Compilation Error

0_0_25189503_21948.cpp: In function 'int main()':
0_0_25189503_21948.cpp:56:21: error: 't' was not declared in this scope
  while(~scanf("%d",&t))
                     ^
0_0_25189503_21948.cpp:66:14: error: 'cmp1' was not declared in this scope
   sort(p,p+t,cmp1);
              ^
0_0_25189503_21948.cpp:67:28: error: 'ecp' was not declared in this scope
   printf("%.2f\n",ecp(0,t-1)/2);
                            ^