View Compilation Error

0_0_38042562_21263.cpp: In function 'int main()':
0_0_38042562_21263.cpp:15:36: error: 'abs' was not declared in this scope
                     max=abs(a[i][j]);
                                    ^
0_0_38042562_21263.cpp:16:31: error: 'abs' was not declared in this scope
                 if(abs(a[i][j])>max)
                               ^