Problem with Code for a Calculator in C++

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C

Ubuntu

I am having a little problem with this code. it is a C++ code and i want to run it in Ubuntu. I have used this code:

#include<stdio.h>

int main() 
{
    int n1,n2,n3; 
    char sym; 
    printf("Welcome to my Calculator\n\n"); 
    printf("Enter the 1st number then the operation you want to perform and then the 2nd number"); 
    scanf("%f%c%f",&n1,&sym,&n2);
    
    if(sym=='+')
    { 
        n3=n1+n2; 
        printf("\n%f",n3); 
    }
    
    if(sym=='-') 
    { 
        n3=n1-n2; 
        printf("\n%f",n3); 
    }
    
    if(sym=='*') 
    { 
        n3=n1*n2; 
        printf("\n%f",n3); 
    }
    
    if(sym=='/') 
    { 
        n3=n1/n2; 
        printf("\n%f",n3); 
    } 
}

I have compiled it by using this command in the terminal:
g++ -Wall -W -Werror Calculator.cpp -o Calculator
and it compiled perfectly. After this I made an executable file of this program by using:
chmod +x Calculator.cpp
it also worked, but after this when I executed my program by this command: ./Calculator
it gave and error:
line 3: syntax error near unexpected token `('
line 3: `int main()'

i can't understand what is the problem please help..