View Compilation Error

0_0_30743215_32547.cpp: In function 'int main()':
0_0_30743215_32547.cpp:6:1: error: 'S' was not declared in this scope
 S=x*(x+1);
 ^
0_0_30743215_32547.cpp:7:1: error: 'T' was not declared in this scope
 T=S/2;
 ^