View Compilation Error

0_0_2156928_2537.cpp:9: error: expected constructor, destructor, or type conversion before '<' token
0_0_2156928_2537.cpp:9: error: expected `,' or `;' before '<' token
0_0_2156928_2537.cpp: In function `void build(int, int, int)':
0_0_2156928_2537.cpp:15: error: `build2' undeclared (first use this function)
0_0_2156928_2537.cpp:15: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_2156928_2537.cpp:15: error: expected `;' before ')' token
0_0_2156928_2537.cpp: In function `int main()':
0_0_2156928_2537.cpp:37: error: `mat' undeclared (first use this function)
0_0_2156928_2537.cpp:53: error: `ans' undeclared (first use this function)
0_0_2156928_2537.cpp:54: error: expected `}' at end of input