I Made A Calculator In C++, Need Help With Decimals!?

Ok, so I made a calculator, and tried using double values for the calculator, but it didn't work too well... Say, for example, if I did 9 divided by 7, it would give me 1. Everything EXCEPT decimals work. If I add 3.7 and 1.3 I get 4. Here is the source:

#include <iostream>

#include <string>

using namespace std;

int add(int, int);

int subtract(int, int);

int multiply(int, int);

int divide(int, int);

int main()

{

long long a, b, c, d, e, f, g;

string h, i, j, k, l, m, n, o, p;

h = "add";

i = "subtract";

j = "multiply";

k = "divide";

hell:

cout << "Hello, please enter what you want to do.\n";

somewhereelse:

cin >> l;

if(l==h)

{

cout << "Please enter the first number.\n";

cin >> a;

cout << "Please enter the second number.\n";

cin >> b;

c = add(a,b);

cout << "The answer is " << c << ".\n";

}

if(l==i)

{

cout << "Please enter the first number.\n";

cin >> a;

cout << "Please enter the second number.\n";

cin >> b;

c = subtract(a,b);

cout << "The answer is " << c << ".\n";

}

if(l==j)

{

cout << "Please enter the first number.\n";

cin >> a;

cout << "Please enter the second number.\n";

cin >> b;

c = multiply(a,b);

cout << "The answer is " << c << ".\n";

}

if(l==k)

{

cout << "Please enter the first number.\n";

cin >> a;

cout << "Please enter the second number.\n";

cin >> b;

c = divide(a,b);

cout << "The answer is " << c << ".\n";

}

if(l!=h && l!=i && l!=j && l!=k)

{

cout << "Please try again.\n";

goto somewhereelse;

}

aplacewhereyoulearntotype:

cout << "Would you like to go again?\n";

cin >> m; n = "yes"; o = "no";

if(m==n)

{

goto hell;

}

if(m==o)

{

cout << "Too bad, maybe next time, eh?\n";

}

if(m!=n && m!=o)

{

cout << "Sorry, please enter \"yes\", or \"no\". Try again.\n";

goto aplacewhereyoulearntotype;

}

return 0;

}

int add(int a, int b)

{

int c =(a+b);

return (c);

}

int subtract(int a, int b)

{

int c =(a-b);

return (c);

}

int multiply(int a, int b)

{

int c =(a*b);

return (c);

}

int divide(int a, int b)

{

int c =(a/b);

return (c);

}

Can you help? Thanks.