View Compilation Error

0_0_15579482_9457.cpp: In function 'atom operator*(atom, atom)':
0_0_15579482_9457.cpp:15:5: error: 'Mat' was not declared in this scope
     Mat c;
     ^
0_0_15579482_9457.cpp:20:21: error: 'c' was not declared in this scope
                     c.x[i][j]=(c.x[i][j]+a.x[i][k]*b.x[k][j])%mo;
                     ^
0_0_15579482_9457.cpp:21:12: error: 'c' was not declared in this scope
     return c;
            ^