View Compilation Error

0_0_17511725_23941.cpp:2:14: error: 'M' was not declared in this scope
 int a ,b,n,j[M],i;
              ^
0_0_17511725_23941.cpp:4:6: error: expected constructor, destructor, or type conversion before '(' token
 scanf("%d%d",&a,&b); //printf("%d %d",a,b); j[i]=a+b; }
      ^
0_0_17511725_23941.cpp:5:1: error: 'i' does not name a type
 i=0;
 ^
0_0_17511725_23941.cpp:6:1: error: expected unqualified-id before 'while'
 while(i<n) {
 ^
0_0_17511725_23941.cpp:8:17: error: expected declaration before '}' token
 printf("\n"); } }
                 ^