write a c program to calculate call charges

#include<stdio.h>

main()
{
    int noc;
    float res;
    printf("Enter the number of callsn");
    scanf("%d",&noc);
    if(noc<=50)
    {
        printf("NILL ! no chargesn");
        
    }
    else if(noc<=100)
    {
        res=noc*0.80;
        printf("charges is %fn",res);
        if(res>250)
        {
                printf("Bill is %f you need to pay it to continue servicesn",res);
        }
    }
    else if(noc<=250)
    {
        res=noc*1.0;
        printf("charges is %fn",res);
        if(res>250)
        {
                printf("Bill is %f you need to pay it to continue servicesn",res);
        }
    }
    else if(noc<=600 || noc<=1000)
    {
        res=noc*1.20;
        printf("charges is %fn",res);
        if(res>250)
        {
            printf("Bill is %f you need to pay it to continue servicesn",res);
        }
    }
    
    else if(noc>1000)
    {
        res=noc*1.50;
        printf("charges is %fn",res);
        if(res>250)
        {
                printf("Bill is %f you need to pay it to continue servicesn",res);
        }
    }
}