View Compilation Error

0_0_28892674_25048.cpp: In function 'int main()':
0_0_28892674_25048.cpp:73:13: error: 'solve' was not declared in this scope
   if (solve()) puts("winnable");
             ^
0_0_28892674_25048.cpp:74:16: error: 'b' was not declared in this scope
   else if (dis[b] > 0) puts("winnable");
                ^