View Compilation Error

0_0_31412335_21496.cpp: In function 'long long int fun(int, int)':
0_0_31412335_21496.cpp:6:17: error: lvalue required as left operand of assignment
 for(int i=1;i<=n=m;i++)
                 ^
0_0_31412335_21496.cpp: In function 'int main()':
0_0_31412335_21496.cpp:18:5: error: 'i' was not declared in this scope
 for(i=2;i<=n;i++)
     ^