How can I change this code, to it doesn´t give warnings of unsigned when compiling

Question

This program gives warnings when I try to compile it it says long unsigned int:

#include <stdio.h>

int main()
{

    int a;
    float b;
    double c;
    char d;

    printf("Size of int=%d bytes\n",sizeof(a));
    printf("Size of float=%d bytes\n",sizeof(b));
    printf("Size of double=%d bytes\n",sizeof(c));
    printf("Size of char=%d byte\n",sizeof(d));

    return 0;
}