View Compilation Error

0_0_7881464_12549.cpp: In function `int solve(int, int)':
0_0_7881464_12549.cpp:18: error: `D' undeclared (first use this function)
0_0_7881464_12549.cpp:18: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_7881464_12549.cpp: At global scope:
0_0_7881464_12549.cpp:26: error: `int D' used prior to declaration