#include<iostream>
#include<stack>
using namespace std;
int precedence(char op) {
if(op == '^') return 3;
else if(op == '*' || op == '/') return 2;
else if(op == '+' || op == '-') return 1;
return -1;
}
string infixToPostfix(string infix) {
stack<char> s;
string postfix = "";
for(int i = 0; i < infix.length(); i++) {
char c = infix[i];
if((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z')) {
postfix = c+postfix;
} else if(c == '(') {
s.push(c);
} else if(c == ')') {
while(!s.empty() && s.top() != '(') {
postfix += s.top();
s.pop();
}
if(!s.empty()) s.pop();
} else {
while(!s.empty() && precedence(s.top()) >= precedence(c)) {
postfix += s.top();
s.pop();
}
s.push(c);
}
}
while(!s.empty()) {
postfix += s.top();
s.pop();
}
return postfix;
}
int main() {
string infix;
cout << "Enter infix expression: ";
cin >> infix;
string postfix = infixToPostfix(infix);
cout << "Postfix expression: " << postfix << endl;
return 0;
}
