```
#include<stdio.h>
int ways(int n,int m)
{
if(n=0) return m;
if(m=0) return n;
else ways(n,m)=ways(n-1,m)+ways(n,m-1); //there is an error here.pls explain//
return ways(n,m);
}
int main()
{
int a,b;
printf("give a and b");
scanf("%d %d",&a,&b);
ways(a,b);
printf("the no of ways from (%d,%d) to (0,0) are %d",a,b,ways(a,b));
return 0;
}
```

what is an lvalue. and whats the wrong in my code in line 6? very curious to know about it. thank you