Inline assembly, error: operand size conflict

I'm trying to write some simple asm code for practice but I get this error: error C2443: operand size conflict

I only want to add 2 numbers and then move the result to another variable.

#include<stdio.h>

int main() {

        int a = 3, b = 3, c;

        __asm {
            mov ax, a;
            mov bx, b;
            add ax, bx;
            mov c, ax;
        }

        printf("%d", c);

    }