foo.cpp: In function 'int main()':
foo.cpp:10:25: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
             if (s[2]='5') 
                         ^
foo.cpp:17:25: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
             if (s[1]='8') cout<<"500";
                         ^
foo.cpp:18:30: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
             else if (s[1]='1') 
                              ^
foo.cpp:36:25: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
             if (s[1]='8') 
                         ^
foo.cpp:42:19: error: 'system' was not declared in this scope
     system("pause");
                   ^